Remove unused etc/ReqMgrConfig.py

This configuration file is IMO not used anywhere. Only considered in the
scenario in which ReqMgr gets deployed along with WMAgent deploy script,
I don't think we run this anywhere. @sfoulkes, please review.
Merge pull request #4560 from zdenekmaxa/reqmgr-remove-unused-config-file

Remove unused etc/ReqMgrConfig.py
Removed GroupUser couchapp from ReqMgr unittests

ReqMgr unittests pushing GroupUser couchapp was not necessary, removed. The
couchapp is not used in ReqMgr at all.
Merge pull request #4565 from zdenekmaxa/reqmgr-remove-groupuser-couchapp-references

Removed GroupUser couchapp from ReqMgr unittests
0.9.63

Signed-off-by: Stephen Foulkes <sfoulkes@fnal.gov>